Re: [syzbot] kernel BUG in ext4_es_cache_extent

From: Phi Nguyen
Date: Sun Feb 13 2022 - 13:03:46 EST

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On 2/6/2022 9:49 PM, syzbot wrote:

Hello,

syzbot found the following issue on:

HEAD commit: 9f7fb8de5d9b Merge tag 'spi-fix-v5.17-rc2' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=148d0304700000
kernel config: https://syzkaller.appspot.com/x/.config?x=b4a89edfcc8f7c74
dashboard link: https://syzkaller.appspot.com/bug?extid=c7358a3cd05ee786eb31
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=124e0abfb00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1758f610700000

Bisection is inconclusive: the issue happens on the oldest tested release.

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=12758738700000
final oops: https://syzkaller.appspot.com/x/report.txt?x=11758738700000
console output: https://syzkaller.appspot.com/x/log.txt?x=16758738700000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c7358a3cd05ee786eb31@xxxxxxxxxxxxxxxxxxxxxxxxx

loop0: detected capacity change from 0 to 1051
EXT4-fs (loop0): ext4_check_descriptors: Checksum for group 0 failed (60935!=0)
EXT4-fs (loop0): mounted filesystem without journal. Quota mode: writeback.
------------[ cut here ]------------
kernel BUG at fs/ext4/extents_status.c:899!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 3587 Comm: syz-executor288 Not tainted 5.17.0-rc2-syzkaller-00039-g9f7fb8de5d9b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:ext4_es_cache_extent+0x4e8/0x550 fs/ext4/extents_status.c:899
Code: 00 48 c7 c7 e0 6c c1 89 c6 05 71 25 6f 0b 01 e8 b0 b6 f6 06 e9 5a ff ff ff e8 94 9d 68 ff 0f 0b e9 d7 fc ff ff e8 88 9d 68 ff <0f> 0b e8 81 9d 68 ff 0f 0b e9 13 fe ff ff e8 25 df af ff e9 c2 fb
RSP: 0018:ffffc90001abee80 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 00000000000013de RCX: 0000000000000000
RDX: ffff88807deb0000 RSI: ffffffff820fd0f8 RDI: 0000000000000003
RBP: ffff888074e6f048 R08: 00000000ffffffff R09: 0000000000000000
R10: ffffffff820fce3c R11: 0000000000000000 R12: 0000000000000001
R13: 00000000ffffffff R14: 1ffff92000357dd1 R15: 00008f1cffffffff
FS: 0000555556ad6300(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f117149e4b0 CR3: 000000007cc1f000 CR4: 0000000000350ee0
Call Trace:
<TASK>
ext4_cache_extents+0x13e/0x2d0 fs/ext4/extents.c:518
ext4_find_extent+0x8f6/0xd10 fs/ext4/extents.c:916
ext4_ext_map_blocks+0x1e2/0x5f30 fs/ext4/extents.c:4098
ext4_map_blocks+0x9ca/0x18a0 fs/ext4/inode.c:563
ext4_getblk+0x553/0x6b0 fs/ext4/inode.c:849
ext4_bread_batch+0x7c/0x550 fs/ext4/inode.c:923
__ext4_find_entry+0x482/0x1050 fs/ext4/namei.c:1600
ext4_lookup_entry fs/ext4/namei.c:1701 [inline]
ext4_lookup fs/ext4/namei.c:1769 [inline]
ext4_lookup+0x4fc/0x730 fs/ext4/namei.c:1760
__lookup_slow+0x24c/0x480 fs/namei.c:1707
lookup_slow fs/namei.c:1724 [inline]
walk_component+0x40f/0x6a0 fs/namei.c:2020
link_path_walk.part.0+0x7ef/0xf70 fs/namei.c:2347
link_path_walk fs/namei.c:2272 [inline]
path_openat+0x266/0x2940 fs/namei.c:3605
do_filp_open+0x1aa/0x400 fs/namei.c:3636
do_sys_openat2+0x16d/0x4d0 fs/open.c:1214
do_sys_open fs/open.c:1230 [inline]
__do_sys_openat fs/open.c:1246 [inline]
__se_sys_openat fs/open.c:1241 [inline]
__x64_sys_openat+0x13f/0x1f0 fs/open.c:1241
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f8e44f22f19
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff98aa3238 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f8e44f22f19
RDX: 000000000000c880 RSI: 0000000020000100 RDI: 0000000000000005
RBP: 00007f8e44ee27b0 R08: 0000000800000015 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f8e44ee2840
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:ext4_es_cache_extent+0x4e8/0x550 fs/ext4/extents_status.c:899
Code: 00 48 c7 c7 e0 6c c1 89 c6 05 71 25 6f 0b 01 e8 b0 b6 f6 06 e9 5a ff ff ff e8 94 9d 68 ff 0f 0b e9 d7 fc ff ff e8 88 9d 68 ff <0f> 0b e8 81 9d 68 ff 0f 0b e9 13 fe ff ff e8 25 df af ff e9 c2 fb
RSP: 0018:ffffc90001abee80 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 00000000000013de RCX: 0000000000000000
RDX: ffff88807deb0000 RSI: ffffffff820fd0f8 RDI: 0000000000000003
RBP: ffff888074e6f048 R08: 00000000ffffffff R09: 0000000000000000
R10: ffffffff820fce3c R11: 0000000000000000 R12: 0000000000000001
R13: 00000000ffffffff R14: 1ffff92000357dd1 R15: 00008f1cffffffff
FS: 0000555556ad6300(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f117149e4b0 CR3: 000000007cc1f000 CR4: 0000000000350ee0

---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches

The non-journal mounted fs is corrupted, syzbot was able to mount it because a [fast commit] patch exclude its inodes from verification process.

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 01c9e4f743ba..385f4ae71573 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4912,7 +4912,7 @@ struct inode *__ext4_iget(struct super_block *sb, unsigned long ino,
goto bad_inode;
} else if (!ext4_has_inline_data(inode)) {
/* validate the block references in the inode */
- if (!(EXT4_SB(sb)->s_mount_state & EXT4_FC_REPLAY) &&
+ if (!(journal && EXT4_SB(sb)->s_mount_state & EXT4_FC_REPLAY) &&
(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
(S_ISLNK(inode->i_mode) &&
!ext4_inode_is_fast_symlink(inode)))) {

Next message: Aaron Tomlin: "Re: [PATCH v5 13/13] module: Move version support into a separate file"
Previous message: Linus Torvalds: "Re: [GIT PULL] sched/urgent for 5.17-rc4"
Next in thread: syzbot: "Re: [syzbot] kernel BUG in ext4_es_cache_extent"
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